/**
 * Copyright (c) 2016 hustcc
 * License: MIT
 * Version: v1.0.1
 * GitHub: https://github.com/hustcc/canvas-nest.js
**/
//封装方法，压缩之后减少文件大小
function get_attribute(node, attr, default_value) {
return node.getAttribute(attr) || default_value;
}
//封装方法，压缩之后减少文件大小
function get_by_tagname(name) {
return document.getElementsByTagName(name);
}
//获取配置参数
function get_config_option() {
	// var scripts = get_by_tagname("script"),
	//   script_len = scripts.length,
	//   script = scripts[script_len - 1]; //当前加载的script
	return {
	  l: Date.parse(new Date()), //长度，用于生成id用
	  z: 0, //z-index
	  o: 1, //opacity
	  c: "40,40,40", //color
	  n: 150 //count
	};
}
//设置canvas的高宽
function set_canvas_size() {
canvas_width = the_canvas.width = window.innerWidth || document.documentElement.clientWidth || document.body.clientWidth, 
canvas_height = the_canvas.height = window.innerHeight || document.documentElement.clientHeight || document.body.clientHeight;
}

//绘制过程
function draw_canvas() {
context.clearRect(0, 0, canvas_width, canvas_height);
//随机的线条和当前位置联合数组
var e, i, d, x_dist, y_dist, dist; //临时节点
//遍历处理每一个点
random_points.forEach(function(r, idx) {
  r.x += r.xa, 
  r.y += r.ya, //移动
  r.xa *= r.x > canvas_width || r.x < 0 ? -1 : 1, 
  r.ya *= r.y > canvas_height || r.y < 0 ? -1 : 1, //碰到边界，反向反弹
  context.fillRect(r.x - 0.5, r.y - 0.5, 1, 1); //绘制一个宽高为1的点
  //从下一个点开始
  for (i = idx + 1; i < all_array.length; i++) {
    e = all_array[i];
    // 当前点存在
    if (null !== e.x && null !== e.y) {
      x_dist = r.x - e.x; //x轴距离 l
      y_dist = r.y - e.y; //y轴距离 n
      dist = x_dist * x_dist + y_dist * y_dist; //总距离, m

      dist < e.max && (e === current_point && dist >= e.max / 2 && (r.x -= 0.03 * x_dist, r.y -= 0.03 * y_dist), //靠近的时候加速
        d = (e.max - dist) / e.max,
        context.beginPath(),
        context.lineWidth = d / 2,
        context.strokeStyle = "rgba(" + config.c + "," + (d + 0.2) + ")",
        context.moveTo(r.x, r.y),
        context.lineTo(e.x, e.y),
        context.stroke());
    }
  }
}), frame_func(draw_canvas);
}
//创建画布，并添加到body中
var the_canvas = document.createElement("canvas"), //画布
config = get_config_option(), //配置
canvas_id = "c_n" + config.l, //canvas id
context = the_canvas.getContext("2d"), canvas_width, canvas_height, 
frame_func = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || window.oRequestAnimationFrame || window.msRequestAnimationFrame || function(func) {
  window.setTimeout(func, 1000 / 45);
}, random = Math.random, 
current_point = {
  x: null, //当前鼠标x
  y: null, //当前鼠标y
  max: 20000 // 圈半径的平方
},
all_array;
the_canvas.id = canvas_id;
the_canvas.style.cssText = "position:fixed;top:0;left:0;z-index:" + config.z + ";opacity:" + config.o;
get_by_tagname("body")[0].appendChild(the_canvas);

//初始化画布大小
set_canvas_size();
window.onresize = set_canvas_size;
//当时鼠标位置存储，离开的时候，释放当前位置信息
window.onmousemove = function(e) {
e = e || window.event;
current_point.x = e.clientX;
current_point.y = e.clientY;
}, window.onmouseout = function() {
current_point.x = null;
current_point.y = null;
};
//随机生成config.n条线位置信息
for (var random_points = [], i = 0; config.n > i; i++) {
var x = random() * canvas_width, //随机位置
  y = random() * canvas_height,
  xa = 2 * random() - 1, //随机运动方向
  ya = 2 * random() - 1;
// 随机点
random_points.push({
  x: x,
  y: y,
  xa: xa,
  ya: ya,
  max: 6000 //沾附距离
});
}
all_array = random_points.concat([current_point]);
//0.1秒后绘制
let canvasTime=setTimeout(function() {
draw_canvas();
}, 100);

export default canvasTime;